Natural stones used in historical buildings often suffer the effects of weathering and degradation processes. In order to preserve and conserve natural building stones, in recent years suitablesynthesized products have been deeply investigated. In the frame of the synthesis of innovative, cheap, eco-friendly, reversible, compatible and high activity products, nanostructured materials represent a cutting edge technology. In particular, TiO2 nanoparticles are an efficient coating product in view ofits self-cleaning photocatalytic action, as testified by the successfully results on Sicilian calcarenite(Bergamonti et al., 2013). However, surface coating could not be a complete solution for conservation purposes, especially when the structural, textural and porosimetric features of the stones requirean integrated preservation and conservation effect both in terms of surface protection and of structural strengthening.Consolidant products are widely used in order to improve durability of building stones and the current researches are focused to test innovative products with high compatibility and low impact. In this work we present the results obtained on the Sabucinastone, a calcarenite outcropping in Central Sicily and widely used as building and replacing stone, by applying coatings based on TiO2 nanoparticles and hybrid organic-inorganic consolidant products also associated with hydrophobic coating. Referring to TiO2nanostructured coating, we tested self-cleaning photocatalytic coatings obtained by sol–gel processat different pH values. Photocatalytic activity of theTiO2 coatings onSabucinastone wasassessed under daylight and ultraviolet irradiation, monitoring methylorange (MeO) and methylene blue (MB) dyes degradation as a function of time. To evaluatethe effect of the treatment, colorimetric and waterabsorption tests were performed. Moreover, in order to verify the efficiency of coating in inhibiting degradation processes, aging tests have been carried out by evaluating stone resistance to salt crystallization. In addition, a network based on aluminum and silicon oxides with epoxidic functional groups has been tested as consolidant product. In order to evaluate its effectiveness, colorimetric, water adsorption, compressive strength, aging tests and mercury porosimetry measurements have been performed. Finally, the performance of an hydrophobic coating applied in association with the consolidanthas been verified by colorimetric and water adsorption tests. In conclusion, the obtained results showgood photodegradation rates for titaniananosols and good protection properties, especially using the basic preparation. Referring to hybrid organic-inorganic strengthen product and hydrophobic coating, preliminary tests highlight promising applications to the preservation of calcarenites. L. BERGAMONTI, I. ALFIERI, A. LORENZI, A. MONTENERO, G. PREDIERI, G. BARONE, P. MAZZOLENI, S. PASQUALE, P.P. LOTTICI, Characterization and photocatalytic activity of TiO2 nanoparticles on Modica and Comiso stones, Applied Surface Science 282, 165-173 (2013)
Nanostructured coating and innovative organic-inorganic consolidant: efficiency tests on a calcarenite from Sabucina (Sicily)
RANERI, SIMONA
2014-01-01
Abstract
Natural stones used in historical buildings often suffer the effects of weathering and degradation processes. In order to preserve and conserve natural building stones, in recent years suitablesynthesized products have been deeply investigated. In the frame of the synthesis of innovative, cheap, eco-friendly, reversible, compatible and high activity products, nanostructured materials represent a cutting edge technology. In particular, TiO2 nanoparticles are an efficient coating product in view ofits self-cleaning photocatalytic action, as testified by the successfully results on Sicilian calcarenite(Bergamonti et al., 2013). However, surface coating could not be a complete solution for conservation purposes, especially when the structural, textural and porosimetric features of the stones requirean integrated preservation and conservation effect both in terms of surface protection and of structural strengthening.Consolidant products are widely used in order to improve durability of building stones and the current researches are focused to test innovative products with high compatibility and low impact. In this work we present the results obtained on the Sabucinastone, a calcarenite outcropping in Central Sicily and widely used as building and replacing stone, by applying coatings based on TiO2 nanoparticles and hybrid organic-inorganic consolidant products also associated with hydrophobic coating. Referring to TiO2nanostructured coating, we tested self-cleaning photocatalytic coatings obtained by sol–gel processat different pH values. Photocatalytic activity of theTiO2 coatings onSabucinastone wasassessed under daylight and ultraviolet irradiation, monitoring methylorange (MeO) and methylene blue (MB) dyes degradation as a function of time. To evaluatethe effect of the treatment, colorimetric and waterabsorption tests were performed. Moreover, in order to verify the efficiency of coating in inhibiting degradation processes, aging tests have been carried out by evaluating stone resistance to salt crystallization. In addition, a network based on aluminum and silicon oxides with epoxidic functional groups has been tested as consolidant product. In order to evaluate its effectiveness, colorimetric, water adsorption, compressive strength, aging tests and mercury porosimetry measurements have been performed. Finally, the performance of an hydrophobic coating applied in association with the consolidanthas been verified by colorimetric and water adsorption tests. In conclusion, the obtained results showgood photodegradation rates for titaniananosols and good protection properties, especially using the basic preparation. Referring to hybrid organic-inorganic strengthen product and hydrophobic coating, preliminary tests highlight promising applications to the preservation of calcarenites. L. BERGAMONTI, I. ALFIERI, A. LORENZI, A. MONTENERO, G. PREDIERI, G. BARONE, P. MAZZOLENI, S. PASQUALE, P.P. LOTTICI, Characterization and photocatalytic activity of TiO2 nanoparticles on Modica and Comiso stones, Applied Surface Science 282, 165-173 (2013)I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
